Core B is the ROS Analytical Core. This is a new core that became necessary because all the projects require quantitative measurement of reactive oxygen species (ROS). Measuring ROS is challenging, particularly when done in vivo, because of multiple intracellular sources of ROS in cells and the known propensity of one form of ROS to readily transform into another. One overriding facet of oxidative stress, however, is peroxidation of unsaturated fatty acid moieties of neutral lipids and phospholipids in cell membranes and oxidation of cellular proteins. Moreover, measuring specific ROS may not explain the functional outcomes in pathological pain and related pathogenesis. An assessment of ROS-induced lipid peroxidation and oxidation of proteins appears to be a logical choice for understanding the underlying mechanism in our pain model. The findings of lipid peroxidation and oxidation proteins will be supported by the real-time live cell and histochemical fixed cell imaging to be conducted in collaboration with Core C. Therefore, ROS Analytical Core will measure lipid peroxidation products and oxidized proteins, and ROS generation in live or fixed cells. The ROS Analytical Core is composed of three branches with an assigned Co-Director for each: 1) Lipid Peroxidation Analysis, 2) Protein Oxidation Analysis, and 3) Histopathology branches. While branches 1) and 2) are for the chemical analysis, branch 3) is to measure intracellular ROS levels using both real-time live-cell imaging and histochemical imaging from fixed cells. For the use of the imaging facility, this core works very closely with Core C (Imaging Core) and the Co-Director of Histopathology of this core is also a Co-Director of the Imaging Core. Therefore, the ROS Analytical Core becomes an integral part of the PPG in delineating the role of ROS in central and peripheral sensitization in pain.